copy from dom/media/gmp-plugin/Makefile.in
copy to dom/media/gmp-plugin-openh264/Makefile.in
--- a/dom/media/gmp-plugin/Makefile.in
+++ b/dom/media/gmp-plugin-openh264/Makefile.in
@@ -1,13 +1,12 @@
 #
 # This Source Code Form is subject to the terms of the Mozilla Public
 # License, v. 2.0. If a copy of the MPL was not distributed with this
 # file, You can obtain one at http://mozilla.org/MPL/2.0/.
 
-INSTALL_TARGETS += FAKE_GMP_PLUGIN
-FAKE_GMP_PLUGIN_DEST = $(DEPTH)/dist/bin/gmp-fake/1.0
-FAKE_GMP_PLUGIN_FILES = \
-  $(SHARED_LIBRARY) \
-  $(srcdir)/fake.info \
-  $(srcdir)/fake.voucher
+INSTALL_TARGETS += FAKE_GMP_OPENH264_PLUGIN
+FAKE_GMP_OPENH264_PLUGIN_DEST = $(DEPTH)/dist/bin/gmp-fakeopenh264/1.0
+FAKE_GMP_OPENH264_PLUGIN_FILES = \
+  $(srcdir)/fakeopenh264.info \
+  $(srcdir)/fakeopenh264.voucher \
+  $(NULL)
 
-include $(topsrcdir)/config/rules.mk

copy from dom/media/gmp-plugin/fake.info
copy to dom/media/gmp-plugin-openh264/fakeopenh264.info
--- a/dom/media/gmp-plugin/fake.info
+++ b/dom/media/gmp-plugin-openh264/fakeopenh264.info
@@ -1,5 +1,4 @@
-Name: fake
+Name: fakeopenh264
 Description: Fake GMP Plugin
 Version: 1.0
-APIs: encode-video[h264], decode-video[h264], eme-decrypt-v7[fake]
-Libraries: dxva2.dll
+APIs: encode-video[h264], decode-video[h264]

copy from dom/media/gmp-plugin/fake.voucher
copy to dom/media/gmp-plugin-openh264/fakeopenh264.voucher
--- a/dom/media/gmp-plugin/fake.voucher
+++ b/dom/media/gmp-plugin-openh264/fakeopenh264.voucher
@@ -1,1 +1,1 @@
-gmp-fake placeholder voucher
\ No newline at end of file
+gmp-fakeopenh264 placeholder voucher

copy from dom/media/gmp-plugin/moz.build
copy to dom/media/gmp-plugin-openh264/moz.build
--- a/dom/media/gmp-plugin/moz.build
+++ b/dom/media/gmp-plugin-openh264/moz.build
@@ -1,22 +1,22 @@
 # -*- Mode: python; c-basic-offset: 4; indent-tabs-mode: nil; tab-width: 40 -*-
 # vim: set filetype=python:
 # This Source Code Form is subject to the terms of the Mozilla Public
 # License, v. 2.0. If a copy of the MPL was not distributed with this
 # file, You can obtain one at http://mozilla.org/MPL/2.0/.
 
-NO_DIST_INSTALL = True
+# largely a copy of dom/media/gmp-fake/moz.build
+
+FINAL_TARGET = 'dist/bin/gmp-fakeopenh264/1.0'
 SOURCES += [
-        'gmp-fake.cpp',
-        'gmp-test-decryptor.cpp',
-        'gmp-test-storage.cpp',
+    '../gmp-plugin/gmp-fake.cpp',
 ]
 
-SharedLibrary("fake")
+SharedLibrary("fakeopenh264")
 
 if CONFIG['OS_ARCH'] == 'WINNT':
     OS_LIBS += [
         'ole32',
     ]
 
 USE_STATIC_LIBS = True
 NO_VISIBILITY_FLAGS = True

--- a/dom/media/gmp-plugin/gmp-fake.cpp
+++ b/dom/media/gmp-plugin/gmp-fake.cpp
@@ -44,20 +44,22 @@
 #include <limits.h>
 
 #include "gmp-platform.h"
 #include "gmp-video-host.h"
 #include "gmp-video-encode.h"
 #include "gmp-video-decode.h"
 #include "gmp-video-frame-i420.h"
 #include "gmp-video-frame-encoded.h"
+
+#if defined(GMP_FAKE_SUPPORT_DECRYPT)
 #include "gmp-decryption.h"
-
 #include "gmp-test-decryptor.h"
 #include "gmp-test-storage.h"
+#endif
 
 #if defined(_MSC_VER)
 #define PUBLIC_FUNC __declspec(dllexport)
 #else
 #define PUBLIC_FUNC
 #endif
 
 #define BIG_FRAME 10000
@@ -402,22 +404,24 @@ extern "C" {
   PUBLIC_FUNC GMPErr
   GMPGetAPI (const char* aApiName, void* aHostAPI, void** aPluginApi) {
     if (!strcmp (aApiName, GMP_API_VIDEO_DECODER)) {
       *aPluginApi = new FakeVideoDecoder (static_cast<GMPVideoHost*> (aHostAPI));
       return GMPNoErr;
     } else if (!strcmp (aApiName, GMP_API_VIDEO_ENCODER)) {
       *aPluginApi = new FakeVideoEncoder (static_cast<GMPVideoHost*> (aHostAPI));
       return GMPNoErr;
+#if defined(GMP_FAKE_SUPPORT_DECRYPT)
     } else if (!strcmp (aApiName, GMP_API_DECRYPTOR)) {
       *aPluginApi = new FakeDecryptor(static_cast<GMPDecryptorHost*> (aHostAPI));
       return GMPNoErr;
     } else if (!strcmp (aApiName, GMP_API_ASYNC_SHUTDOWN)) {
       *aPluginApi = new TestAsyncShutdown(static_cast<GMPAsyncShutdownHost*> (aHostAPI));
       return GMPNoErr;
+#endif
     }
     return GMPGenericErr;
   }
 
   PUBLIC_FUNC void
   GMPShutdown (void) {
     g_platform_api = NULL;
   }

--- a/dom/media/gmp-plugin/moz.build
+++ b/dom/media/gmp-plugin/moz.build
@@ -6,16 +6,18 @@
 
 NO_DIST_INSTALL = True
 SOURCES += [
         'gmp-fake.cpp',
         'gmp-test-decryptor.cpp',
         'gmp-test-storage.cpp',
 ]
 
+DEFINES['GMP_FAKE_SUPPORT_DECRYPT'] = True
+
 SharedLibrary("fake")
 
 if CONFIG['OS_ARCH'] == 'WINNT':
     OS_LIBS += [
         'ole32',
     ]
 
 USE_STATIC_LIBS = True

--- a/dom/media/moz.build
+++ b/dom/media/moz.build
@@ -18,16 +18,17 @@ with Files('RTC*'):
 component_av = ('Core', 'WebRTC: Audio/Video')
 with Files('GetUserMedia*'):
     BUG_COMPONENT = component_av
 
 DIRS += [
     'encoder',
     'gmp',
     'gmp-plugin',
+    'gmp-plugin-openh264',
     'imagecapture',
     'mediasource',
     'ogg',
     'systemservices',
     'webaudio',
     'webrtc',
     'webspeech',
     'webvtt',

--- a/python/mozbuild/mozbuild/mach_commands.py
+++ b/python/mozbuild/mozbuild/mach_commands.py
@@ -671,17 +671,20 @@ class GTestCommands(MachCommandBase):
 
         # Use GTest environment variable to control test execution
         # For details see:
         # https://code.google.com/p/googletest/wiki/AdvancedGuide#Running_Test_Programs:_Advanced_Options
         gtest_env = {b'GTEST_FILTER': gtest_filter}
 
         xre_path = os.path.join(self.topobjdir, "dist", "bin")
         gtest_env["MOZ_XRE_DIR"] = xre_path
-        gtest_env["MOZ_GMP_PATH"] = os.path.join(xre_path, "gmp-fake", "1.0")
+        gtest_env["MOZ_GMP_PATH"] = os.pathsep.join(
+            os.path.join(xre_path, p, "1.0")
+            for p in ('gmp-fake', 'gmp-fakeopenh264')
+        )
 
         gtest_env[b"MOZ_RUN_GTEST"] = b"True"
 
         if shuffle:
             gtest_env[b"GTEST_SHUFFLE"] = b"True"
 
         if tbpl_parser:
             gtest_env[b"MOZ_TBPL_PARSER"] = b"True"

--- a/testing/gtest/rungtests.py
+++ b/testing/gtest/rungtests.py
@@ -62,17 +62,20 @@ class GTests(object):
         return result
 
     def build_core_environment(self, env = {}):
         """
         Add environment variables likely to be used across all platforms, including remote systems.
         """
         env["MOZILLA_FIVE_HOME"] = self.xre_path
         env["MOZ_XRE_DIR"] = self.xre_path
-        env["MOZ_GMP_PATH"] = os.path.join(self.xre_path, "gmp-fake", "1.0")
+        env["MOZ_GMP_PATH"] = os.pathsep.join(
+            os.path.join(self.xre_path, p, "1.0")
+            for p in ('gmp-fake', 'gmp-fakeopenh264')
+        )
         env["XPCOM_DEBUG_BREAK"] = "stack-and-abort"
         env["MOZ_CRASHREPORTER_NO_REPORT"] = "1"
         env["MOZ_CRASHREPORTER"] = "1"
         env["MOZ_RUN_GTEST"] = "1"
         # Normally we run with GTest default output, override this to use the TBPL test format.
         env["MOZ_TBPL_PARSER"] = "1"
 
         if not mozinfo.has_sandbox:

--- a/testing/mochitest/Makefile.in
+++ b/testing/mochitest/Makefile.in
@@ -81,16 +81,17 @@ TEST_HARNESS_PLUGINS := \
 endif
 
 # Rules for staging the necessary harness bits for a test package
 PKG_STAGE = $(DIST)/test-stage
 DIST_BIN = $(DIST)/bin
 
 GMP_TEST_PLUGIN_DIRS := \
   $(DIST_BIN)/gmp-fake \
+  $(DIST_BIN)/gmp-fakeopenh264 \
   $(DIST_BIN)/gmp-clearkey \
   $(NULL)
 
 $(_DEST_DIR):
 	$(NSINSTALL) -D $@
 
 # On Android only, include a release signed Robocop APK in the test package.
 ifeq ($(MOZ_BUILD_APP),mobile/android)

--- a/testing/mochitest/mach_commands.py
+++ b/testing/mochitest/mach_commands.py
@@ -452,25 +452,24 @@ class MochitestRunner(MozbuildObject):
             if app_override == "dist":
                 options.app = self.get_binary_path(where='staged-package')
             elif app_override:
                 options.app = app_override
             if options.gmp_path is None:
                 # Need to fix the location of gmp_fake which might not be
                 # shipped in the binary
                 bin_path = self.get_binary_path()
-                options.gmp_path = os.path.join(
-                    os.path.dirname(bin_path),
-                    'gmp-fake',
-                    '1.0')
-                options.gmp_path += os.pathsep
-                options.gmp_path += os.path.join(
-                    os.path.dirname(bin_path),
-                    'gmp-clearkey',
-                    '0.1')
+                gmp_modules = (
+                    ('gmp-fake', '1.0'),
+                    ('gmp-clearkey', '0.1'),
+                    ('gmp-fakeopenh264', '1.0')
+                )
+                options.gmp_path = os.pathsep.join(
+                    os.path.join(os.path.dirname(bin_path), *p)
+                    for p in gmp_modules)
 
         logger_options = {
             key: value for key,
             value in vars(options).iteritems() if key.startswith('log')}
         runner = mochitest.Mochitest(logger_options)
         options = opts.verifyOptions(options, runner)
 
         if options is None:

--- a/testing/mochitest/runtests.py
+++ b/testing/mochitest/runtests.py
@@ -1446,16 +1446,17 @@ class Mochitest(MochitestUtilsMixin):
             options.xrePath,
             # For packaged builds, GMP plugins will get copied under
             # $profile/plugins.
             os.path.join(self.profile.profile, 'plugins'),
         ]
 
         gmp_subdirs = [
             os.path.join('gmp-fake', '1.0'),
+            os.path.join('gmp-fakeopenh264', '1.0'),
             os.path.join('gmp-clearkey', '0.1'),
         ]
 
         gmp_paths = [os.path.join(parent, sub)
                      for parent in gmp_parentdirs
                      for sub in gmp_subdirs
                      if os.path.isdir(os.path.join(parent, sub))]